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Constraints on the exhumation and erosion of the High Himalayan Slab, NW India, from foreland basin deposits.

White, Nikki M. and Pringle, M. and Garzanti, E. and Bickle, M. and Najman, Y. and Chapman, H. (2002) Constraints on the exhumation and erosion of the High Himalayan Slab, NW India, from foreland basin deposits. Earth and Planetary Science Letters, 195 (1-2). pp. 29-44. ISSN 0012-821X

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Abstract

Petrography, Sr–Nd isotope compositions and single-grain laser 40Ar–39Ar ages of detrital white mica from Early–Middle Miocene molasse of the Dharamsala and Lower Siwalik Formations of Northern India, dated by magnetostratigraphy, determine the sediment sources, their metamorphic grade and exhumation rates in the Himalayan palaeo-hinterland. Deposition of the Lower Dharamsala Member (21–17 Ma) occurred during the period of rapid isothermal decompression and crustal anatexis (24–18 Ma) of the metamorphic core. This episode of decompression is thought to be coeval with thrusting on the Main Central Thrust and normal faulting on the South Tibetan Detachment System. The sediment composition and detrital mica ages indicate erosion from the rapidly exhumed metamorphic slab of the High Himalayan Crystalline Series. Deposition of the Upper Dharamsala Member (17–13 Ma) and basal Siwalik Group (13–12.5 Ma) spanned the period in which thrusting transferred south from the Main Central Thrust. The sediment composition and detrital mica ages contrast strongly with those of the Lower Dharamsala, indicating erosion from sedimentary and low grade rocks. The isotopic composition indicates that these rocks were part of the High Himalayan Series unaffected by Tertiary metamorphism, i.e. from upper structural levels of the High Himalayan Slab. This suggests that a major reorganisation of the orogenic wedge occurred at 17 Ma involving forward propagation of the MCT and cessation of rapid exhumation of the metamorphic slab.

Item Type: Article
Journal or Publication Title: Earth and Planetary Science Letters
Additional Information: White was my PhD student, other co-authors provided analyses. This was one of the first papers to demonstrate an integrated use of techniques in the 'detrital approach' towards solving tectonic problems. It provided insights into crustal deformation models. RAE_import_type : Journal article RAE_uoa_type : Earth Systems and Environmental Sciences
Uncontrolled Keywords: Himalayas ; exhumation ; Siwalik System ; provenance
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 2126
Deposited By: ep_importer
Deposited On: 08 Apr 2008 10:09
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 15:44
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/2126

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